1. Technical Field of the Invention
The present invention relates generally to a manufacturing method of a sensor element of a gas sensor provided with an electrode terminal and a terminal installation jig used to install the electrode terminal on the sensor element without causing any damage to the sensor element.
2. Background Art
Japanese Patent Second Publication No. 6-3430 discloses a typical gas sensor consisting of a hollow cylindrical sensor element and an inner electrode installed in the sensor element. The inner electrode terminal is made up of an annular holder and a lead extending from the annular holder. The annular holder is connected electrically with one of electrodes installed in the sensor element. The lead is connected electrically with an external device.
The annular holder has an outer diameter greater than an inner diameter of the inner terminal mount and is press-fitted to an inner terminal mount formed on an inner surface of the sensor element. The installation of the inner electrode terminal is achieved by compressing the annular holder inwardly and inserting it into an end opening of the sensor element.
It is, however, relatively difficult to compress the annular holder to decrease the outer diameter thereof to the degree required for insertion into the end opening of the sensor element. A failure in such compression may result in collision of the annular holder with the end of the sensor element, which causes the damage to the sensor element. The same applies to the outer electrode holder.